Polarographische Reduktion von β-Aminovinyliminen der Indenreihe

Polarographic Reduction of β-Aminovinylimines of the Indene Series The mechanism of electrolytic reduction of aminovinylimine (AVI) is suggested, based on results of the identification of electrolysis products and on the dependence of polarographic curves. It is shown that this mechanism becomes complicated by the kinetics of hydrolysis of starting substances and intermediates. The determination of complex forming constants for AVI and bovine serum albumine is determined and compared by polarography and spectroscopy.     

Die copolymerisation von styrol und α-methylstyrol mit hilfe von alkyllithium-verbindungen. 1. Mitteilung: Untersuchung der Copolymerisation von Styrol und α-Methylstyrol mit n-Butyllithium als Initiator und Hexamethylphosphorsäuretriamid als Beschleuniger

The amount of α-methylstyrene incorporated into the copolymer with styrene depends on the amount of hexamethylphosphoramide (HMPA) employed. It increases with increasing HMPA concentrations. Using an equimolar monomer mixture copolymers with α-methylstyrene contents of almost 50% can be obtained; decreasing butyllithium concentrations at a constant ratio of HMPA to n-butyllithium yield copolymers with decreasing α-methylstyrene contents, while at a constant HMPA concentration but decreasing n-butyllithium concentrations copolymers with constant α-methylstyrene contents are obtained.     

Cyclisierungsreaktionen β,γ-ungesättigter Kohlensäurederivate. V . Reaktionen β,γ-ungesättigter Carbamidsäureester mit Sulfenylchloriden - Synthese von 3,5,5-trisubstituierten Oxazolidin-2-onen

Cyclization Reactions of β,γ-Unsaturated Derivatives of Carbonic Acid. V. Reactions of β,γ-Unsaturated Carbamic Acid Esters with Sulfenyl Chlorides — Synthesis of 3,5,5-Trisubstituted Oxazolidine-2-ones N,N-Disubstituted β,γ-Unsaturated urethanes 1 have been cyclized to 3,5,5-trisubstituted oxazolidine-2-ones 3 by aromatic sulfenyl chlorides in methylene chloride. The same oxazolidine-2-ones 3 were obtained by reaction of 5-bromomethyloxazolidine-2-ones 8 with thiophenols.     

Zur copolymerisation von α-methylstyrol und butadien. V. Bestimmung der chemischen heterogenität durch gelchromatographie

The distribution function of the compositional heterogeneity of copolymers from α-methyl styrene and butadiene has been determined from gel permeation chromatography by detection of refractive index and ultraviolet absorption.     

Raman investigations of NH3 adsorption on TiO2, Nb2O5, and Nb2O5/TiO2

A study has been carried out of the interactions of NH₃ with TiO₂, Nb₂O₅, and Nb₂O₅/TiO₂. Raman spectroscopy was used to characterize the structure of the adsorbed NH₃ and perturbations of species present at the surface of the adsorbent. On each oxide, NH₃ adsorbs predominantly at Lewis acid sites. Hydrogen-bonding occurs between the adsorbed NH₃ and OH groups present on the surface of TiO₂. A small concentration of NH ₄ ⁺ is observed, consistent with the relatively low concentration of Brønsted acid sites compared to Lewis acid sites on each of the samples investigated. Exposure of Nb₂O₅/TiO₂ to NH₃ at temperatures up to 500°C does not result in partial reduction of the supported niobia.     

Die Reaktion von α,β-Dihalogen-propionitrilen mit monosubstituierten Hydrazinen - einfache Synthese 1-substituierter 3- bzw. 5-Amino-pyrazole

The Reaction of α,β-Dihalogeno-propionitriles with Monosubstituted Hydrazines — A Simple Synthesis of 1-Substituted 3- or 5-Amino-pyrazoles In methanol hydrazines 3 , and α,β-dihalogeno-propionitriles 1, 2 even at 0°C irreversibly yield 3 · HX, and α-halogenoacrylonitriles 4, 5 (A₁). Fast addition of alkyl- and aralkyl- hydrazines 3 to 4, 5 (C) gives 1-substituted 1-(2′-halogeno-2′-cyan-ethyl)-hydrazines 6 , the addition of arylhydrazines 3 to 4, 5 (D) 1-aryl-2-(2′-halogeno-2′-cyan-ethyl)-hydrazines 8 . In methanol 6 spontaneously cyclise (E) to hydrogen halides 7 · HX of 1-alkyl- and 1-aralkyl-3-amino-pyrazoles, 8 with 2 moles of acids (F) to salts 10 · 2HY of 1-aryl-4-halogeno-5-imino-pyrazolidines, and the free 10 spontaneously (G) to hydrogen halides 9 · HX of 1-aryl-5-amino-pyrazoles. Mechanisms (A₁), (C), (D), (E), (F), and (G) are proved by t.l.c., ¹H-n.m.r., and isolation of intermediates, the structures of 7 resp. 9 , using the significant ¹H-n.m.r.-parameter Δ. Simple general syntheses are described for 3-amino-pyrazoles 7 (R = H, alkyl, aralkyl) or 5-amino-pyrazoles 9 (R = aryl) starting with α,β-dihalogeno-propionitriles 1, 2 , and for α-bromo-acrylonitrile 5 .